Apparatus for casting zinc slabs and the like



Patented Nov. 25, 1930 NIT D STATES PATENT OFFICE DANIEL H. GRAY AND JOHN J. WILLIAMS, 0] WHEELING, WEST VIRGINIA, ASSIGNORS '10 HAZEL-ATLAS GLASS 00., O! WHEEL WEST VIRGINIA ING, 'WEST VIRGINIA, A. CORPORATION OF 'srraaarus FORCASTING zmc suns AND THE LIKE Application flled october 27, 1928. Serial No. 815,518.

In the casting of slabs of zinc as well as other metals it is desirable that the metal forming the slab beas' nearly pure as is possible under practical working conditions in the factor Even more desirable is the pre-,

vention o blow-holes or gas holes in the finfore, resides in the provision'of an apparatus and method ofcasting slabs of metal in a partial vacuum so as to eliminate the blow-holes or the like heretofore resent in such castings.

A further object o? theinvention consists in the provision of a novel apparatus by .means of which the molten metal is drawn diby avoidin any possibility of a partial oxidation of t e mold. 4

Another object of the invention resides in metal prior to its entering the the provision of such an apparatus which isrelat1vel simple and mexpensive 1n construc-:

tion an which is so designed as to apply a vacuum in the most ex editions manner t produce the desired resuts. i Prior attem ts have been made to cast metal slabs an the like in vacuo, but such devices have not gone into eneral use because of serious defects in t e principal of o oration as; well as for various other reasons w ich are well known to thoseskilled in the art. While the present invention about to be described in'detail is more particularly concerned with the casting of zinc slabs it will be readily apparent that both the process and .more speci serves to prevent an apparatus are also well adapted to the casting of other metals. i

In the drawings:

The figure is a side elevational view of a.

furnace in assembled relation with the vacuum apparatus and the casting mechanism,- certain of the parts being shown in section.

' Referrin to the accompanying drawing %cally, the numeral 1 designates the forward end of a pot or furnace in which the molten zinc is prepared for casting. Adjacent the pot 1 is mounted thecasti'ng mechanism which is designated generally by the numeral 2, and comprises a table 3 mounted for rotation on a circular track 4. Supported on the table 3 are a plurality of inclined casting molds 5 which are of; substantially air-tight construction and supported by means of plates 6 and braces 7 and 8. a

As will appear from an inspection of the drawing, the molds 5'are formed of two hinged sections, and are longitudinally adjustable along the supporting plates 6 by means of screws 9 which are threaded into sockets 10 on the table 3 and have their u per ends in engagement with the lower en s of the molds 5. Handles 9 are fixed to the screws 9 for conveniently operating them. These molds, as already mentioned, are of substantially air-tight construction, and are provided at their u r ends with necks 11 aving flan es 12 w ich are'adapted to form a ground joint with the vacuum system about tobe described. I

For the purpose of'withdrawingthe molten metal from a point substantially midway between its to and bottom surfaces a pipe 13 is su porte by any conventional means in a partiy submerged position on the pot 1. This pipe 13 forms part of a conduit 15 leading to a vacuum pump 16 and which conduit is provided with an air valve 17. The conduit 15 is provided with a branch pi e or conduit 18 for cooperation with the mo ds 5 and is also provided with a vacuum tank or trap 19 which 7 liability of molten metal bein drawn through the conduit to the pum 16. n this connection it may be mentions that the conduit 15 extends vertically above the; surface of the molten metal in pot 1 to a distance of at least 60" thereby avoiding, under ordina conditions, any possibility of the metal reac ing the horizontal portion of the conduit.

Branch conduit 18 is provided with a circular flange 20 corresponding to the 'flange 12 on each of the molds 5 and is provided with a ground seating surface or with a packing so as to provide an air-tight joint with the neck of a mold when clamped thereto by means of suitable clamps such as depicted on the drawing and designated by numeral 21. It will, of course, be understood that each of the molds 5 is brought successively to conduit 18 and clamped in position for the casting operation, and that the mold may be adusted longitudinally by its screw 9 to the desired extent.

' In order to avoid any possibility of the molten metal freezing in pipe 13 when the device is first put in operation and before the conduit has become sufiiciently heated, a burner or heater 22 is placed around this pipe and supplied with proper fuel by means of a pipe line 23; the burner being suported by a V bracket 14.

In the operation of the device the molten metal is, of course, first prepared for casting and one of the molds 5 then connected up to the vacuum system as'indicatedon the drawing. The vacuum pump 16 is then started and in addition to withdrawing air from the conduit 15 and mold 5 also serves to remove dissolved gases in the molten metal as the latter rises in the pipe 13. This molten metal is drawn from the intermediate layers in the pot 1 and is therefore free of impurities such as are normally found on the bottom of such pots or floating u on the surface of the molten metal. The point at which the metal flows over from conduit 15 into pipe 18 is about 50 above the surface of the molten metal, and inasmuch as a vacuum of 27 of mercury is capable of lifting a column of molten zinc approximately 54", it will be apparent that the entire apparatus including the mold- 5 will be exhausted to a vacuum of.

approximately 25" before thelevel of the zinc in pipe 13 reaches the branch. conduit 18. Hence as the metal flows through conduit 18 down into mold 5 it will enter a vacuumized chamber thereby avoiding any possibility of entrapping air and forming blow holes in the finished product. When the mold is filled the pump 16 is shut ofi or opened to atmosphere by valves 17 thus allowing the metal in pipe 13 to return to the pot. A small amount of the molten metal may remain in conduit 18 above the mold 5 when the latter is released from its connection with the branch conduit, but such material may readily be caught in a trough and allowed to flow back to the pot. The filled mold is wheeled away and a new one 'brou ht up to the casting station by the rotation o the table 3, so that the procedure may be repeated indefinitely while the supply of molten metal continues.

From the foregoing description. of the apparatus and the method of operation, it Wlll be obvious that the molten metal is transferred from the pot to the mold without contact with the atmosphere, thus avoiding any oxidation of the metal in the casting operation. It will also be noted thatthe transfer of impurities from the pot to the mold is avoided, and that by reason of castingin vacuo the formation of gas and blow holes in the finished casting is greatly reduced if not entirely eliminated.

In accordance with the patent statutes We have described what we now believe to be the .best embodiment of the apparatus for and the method of casting metal slabs, but it is to be understood that both the drawing and'description are intended merely as illustrative of the invention and that the invention is susceptible of various changes without departing from the spirit of the invention.

Having fully described our invention, what we claim as new. and desire to secure by Letters Patent is:

1. Casting apparatus for metal slabs, including a furnace for the molten metal, a substantially air-tight mold adjacent said furnace, a source of vacuum, communicating conduits leading from the source of vacuum to said furnace and mold, and a heater associated with one of said conduits.

2. Casting apparatus for metal slabs, including a furnace for the molten metal, a substantiall air-tight mold adjacent said furnace an extending to a point located at a substantial distance above the surface of the metal in the furnace, a source of vacuum, a conduit leadin from the source of vacuum downwardly an extending into the metal insaid furnace, a branch conduit associated with said first-mentioned conduit, and means for forming a substantially air-tight connection between said branch conduit and said mold.

3. Casting apparatus for metal slabs, including a furnace for the molten metal, a substantially air-tight mold adjacent said furnace, a source of vacuum, communicating conduits leading from said source of men um to said furnace and said mold, and a trap for molten metal associated with one of said conduits.-

4. Casting apparatus for metal slabs, including a furnace for the molten metal, a substantially air-tight mold adjacent said furnace, a source of vacuum, a conduit leading from the source of vacuum to said furnace, a branch conduit communicating with said first-mentioned conduit at a point substantially 50" above the plane of the surface of the molten m tal, and. means for connecting the end of the branch conduit with the mold.

5. Castin apparatus formetal slabs, in-

I cluding a urnace for the molten metal, a

substantially air-tight mold adjacent said furnace, a source of vacuum, a conduit leading from the source'of vacuum and terminating in said furnace at a point substantially midway between the bottom of said tank and the surface of the molten metal,

and a branch conduit leading from said firstmentioned conduit to said mold.

,6. Castin apparatus for metal slabs, including a urnace for the molten metal, a substantially air-tight mold adjacent said furnace, a source of vacuum, a conduit leading from the source of vacuum to said furnace, a branch conduit leading to said mold,

and means for adjusting the position .of the mold with respect to its conduit.

7. Castin apparatus for metal slabs including a urnace for the molten metal, a'

. substantially air-tightmold adjacent said furnace, a vacuum tank, a pump associated therewith,'a conduit leading from said tank to the furnace, a branch conduit connected to the first-mentioned conduit at a int high- 'er than the level of the metal in t e furnace and'leading to the mold. 4

' v DANIEL M. GRAY.

JOHN J. WILLL AMS. 

